// Copyright (C) Kumo inc. and its affiliates.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//
#pragma once

#include <pollux/functions/macros.h>

namespace kumo::pollux::functions::sparksql {
    /// concat(array1, array2, ..., arrayN) → array
    /// Concatenates the arrays array1, array2, ..., arrayN. This function
    /// provides the same functionality as the SQL-standard concatenation
    /// operator (||).
    template<typename TExec, typename T>
    struct ArrayConcatFunction {
        POLLUX_DEFINE_FUNCTION_TYPES(TExec)

        static constexpr int32_t kMaxElements = INT32_MAX - 15;

        void call(
            out_type<Array<T> > &out,
            const arg_type<Variadic<Array<T> > > &arrays) {
            size_t elementCount = 0;
            for (const auto &array: arrays) {
                elementCount += array.value().size();
            }
            POLLUX_USER_CHECK_LE(
                elementCount,
                kMaxElements,
                "Unsuccessful try to concat arrays with {} elements due to exceeding the array size limit {}.",
                elementCount,
                kMaxElements);
            out.reserve(elementCount);
            for (const auto &array: arrays) {
                out.add_items(array.value());
            }
        }
    };
} // namespace kumo::pollux::functions::sparksql
